Abstract 15795: Prehospital Use of Nasal Cannula End-tidal CO2 Monitoring in Non-intubated Major Traumatic Brain Injury Patients
Background: Little is known about end-tidal CO2 monitoring using nasal cannula sensors in non-intubated patients (NC-ETCO2). Objective: To describe the patterns of NC-ETCO2 seen during the EMS care of spontaneously-breathing, major Traumatic Brain Injury (TBI) patients.
Methods: Continuous NC-ETCO2 data were evaluated from a subset of non-intubated, major (moderate or severe) TBI cases (4/24/13-4/20/15) in the EPIC TBI Study (NIH-1R01NS071049). Cases from 4 EMS agencies that are reporting monitor data (Philips MRx™ monitors) were included. Descriptive statistics were used to evaluate case and NC-ETCO2 attributes.
Results: Among the 56 cases included, median age was 51 (range 10-91; 63% male). 91% had median respiratory rate (RR) >15/min and 57% had median RR >20. Six cases (11%) had a median NC-ETCO2 <20 mmHg, 45% (25) were 20-29, 21% (12) were 30-34, 23% (13) were 35-45 mmHg. No case had a median NC-ETCO2 >45. Several common NC-ETCO2 patterns emerged: 1) while the final level varied among patients, the vast majority of cases (46; 82%) attained a stable “plateau” with relatively small variation after that point; 2) ETCO2 often “ramped up” from <10 mmHg to the plateau during the initial 10-30 sec of monitoring (24; 43%); 3) many patients (34; 61%) had near-normal (30-34 mmHg) or even normal (35-45) ETCO2 plateaus. In 70% of the cases with normal ETCO2 plateaus, these levels were maintained despite high RR and/or dramatic variations in RR.
Conclusion: We believe this is the first report of the use of NC-ETCO2 monitoring in non-intubated EMS patients. After initial “ramp up,” the vast majority of cases achieved stable readings even though dramatic variations in RR were common. Most patients (57%) were spontaneously hyperventilating at rates more than twice “normal.” Despite this, over half of them had ETCO2 plateaus that were normal or near-normal throughout their course. It is unclear whether the “very low” readings (<30 mmHg) represent true physiological hypocapnea or simply “washout” due to the sensors being in an open ventilatory space (the naris) with continuous ambient O2 flow. Future studies comparing NC-ETCO2 to measured arterial pCO2 are needed to identify their correlation and the accuracy of NC-ETCO2 as a tool for evaluating ventilatory physiology.
Author Disclosures: B.J. Barnhart: Research Grant; Significant; Philips Healthcare. D.W. Spaite: None. E. Helfenbein: Employment; Significant; Philips Healthcare. Ownership Interest; Modest; Philips Stock. O. Perez: Research Grant; Significant; Philips Healthcare. S. Babaeizadeh: Employment; Significant; Philips Healthcare. C. Hu: None. V. Chikani: None. J.B. Gaither: None. K.R. Denninghoff: None. S.M. Keim: None. C. Viscusi: None. D. Sherrill: None. B.J. Bobrow: None.
- © 2016 by American Heart Association, Inc.